Being the eldest son of the family, Katsumi puts the importance of family above everything else. One of the biggest instances is his decision to abandon his lifelong dream of becoming a baseball player to support his father's specialty store ever since his mother disappeared. This, in turn, allows him to develop a keen fashion sense and determine the best clothes for his clients.
Although Katsumi sometimes quarrels with Isami, both of them willingly cooperate with each other when facing opponents. Despite being a critical thinker, he is also hot-blooded and incapable of observing his surroundings when playing baseball.
Katsumi encountered Grigio Bone on his missing mother's birthday and received both R/B Crystals and R/B Gyro while fleeing for his life. After his initial fight as Rosso, Katsumi became hesitant due to the responsibility of an Ultraman until an encounter with Black King changed his mind. Ever since then, he would join Isami in fighting as Ultramen to defend the city against monster attacks.
While training for his coach's baseball match, Katsumi's determination puts him in a dilemma for either saving the city or winning a match. Fortunately, said coach took his place as a batter while Katsumi halted Red King's assault with the three Crystals he obtained earlier.
Unknowingly to them, their battles were being watched and analyzed by Makoto himself, who presented them with several trials such as capturing an old friend within Mecha Gomora. When Makoto revealed to them his true nature and origins, the brothers fight against him directly, when he transforms into Ultraman Orb Dark and they were easily defeated.
After that, Katsumi and Isami set out to do some training in the mountains so that they could beat Orb Dark. On their second training session, the brothers with some indirect help from Asahi found the Victory Crystal in a cave, granting them the power of Earth. With this new power and their training, they challenged Orb Dark to a rematch and defeated him. The brothers then took the Orb Ring NEO from Makoto.
Later, the next challenge they faced was Horoboros, who the brothers lose to despite having the Orb Ring NEO. After their defeat, Makoto reclaims the device and transforms into Orb Dark to fight Horoboros. Unable to transform, the brothers could only watch Makoto fight the beast and after his "victory", they confront him in public, telling everyone that he is behind the monster attacks but nobody believes them. Isami gets upset, so Katsumi reminds them about why they fight as Ultraman and that cheers him up. The next day, Makoto summons Bezelb to fight it as Orb Dark to further promote himself but the brothers show up and defeat the Bezelb before he could, angering him. Orb Dark tries to attack them but Horoboros reappears and evolves.
It defeats Rosso, Blu, and Orb Dark before disappearing, but Katsumi and Isami are badly injured in the process and they detransform in from of Asahi, who finds out about their alter egos before the two of them are sent to a hospital for treatment. After they reawaken, they try desperately to hide their identities from Asahi but it is too late. Horoboros appears yet again and the two brothers transform and fight, coming up with a strategy to put it in hardened stone, but it failed. With Asahi returning the Orb Ring NEO to them, they used its power and finished off Horoboros with the Triple Origium Beam.
After that, they were faced by a vengeful Cereza, who transformed into Grigio King via Saki's Gyro. The brothers try their best but they are unable to defeat Grigio King, exhausting all of their techniques. The brothers return the next day after a short recovery period, but even with a new strategy, they were unable to defeat Grigio King until Asahi reminded them of their mother's words - that when the two of them are together, they can do anything. With that, they unlocked the power of Ultraman Ruebe, who fought Grigio King and destroyed it.
Katsumi and Isami meet Saki Mitsurugi several times, mostly while she is with Asahi and they find out that she is behind the recent monster attacks. The two of them become suspicious and further antagonize her when she announces her plan to turn Earth into a bomb to destroy Leugocyte. Later on, the brothers had their Gyros stolen by Saki Mitsurugi after King Joe attacks. Back at Quattro M, Asahi explains to the brothers about Saki's past and while Katsumi sympathizes with her, Isami is determined to stop her. Confronting Saki to get back their stolen Gyros when Gomora attacks, they also try to convince her that defeating Leugocyte at the cost of the planet is not what her brothers would have wanted, but she disagrees. The brothers fight her as Grand King Megalos and defeat her though Katsumi was hesitant to fight while Isami attacked without a doubt. After she tells them what happened to their mother, Mio, she transforms into Horoboros but like before, Katsumi hesitated in fighting her. This disagreement causes the brothers to not be able to use the power of Ruebe but after clearing their disagreements and deciding to protect what is important to them; their family, they can once again use the power of Ruebe, which they used to beat Saki but not finish her off. After chasing Saki back to a lab, the brothers and Asahi witnessed the return of Mio Minato.
Back at the Quattro M shop, Mio explained everything that happened during her time in the alternate dimension and knew that her sons became Ultramen. She even knew about the approaching Leugocyte and told her family about it. After Ruebe finishes off Kamisori Demaaga, Mio incapacitates her sons and steals their Gyros as part of a plan to stop Leugocyte. After seeing Leugocyte get turned into a R/B Crystal, Katsumi and Isami confronted their mother, saying that they would have just given her the Gyros if she had asked. She then asked the boys for help in disposing of the crystal by throwing it into the dimension they came from. Just as the boys were about to do so, Saki took back her Gyro, closing the portal and taking the Leugocyte Crystal. After leaving, Mio tells her sons not to fight because she saw the outcome while in the other dimension; which was Rosso and Blu getting destroyed by Leugocyte. Katsumi and Isami reassure their mother that they will protect the planet and run off to find Saki. They saw her at a cafe talking to Asahi and followed her when she left. Katsumi and Isami try to talk her out of detonating the planet, but they failed to persuade her. After fighting as Rosso and Blu, and then Ruebe, the brothers are defeated. After Leugocyte was set free from its imprisonment, Katsumi and Isami could only watch as the Cosmo Eater arrived.
Katsumi and Isami passed out after their defeat, but they were found by Ushio and Asahi with the former taking the R/B Gyros as well. When they reawakened, the brothers had to get Ushio to give them back their Gyros, which were taken from them as Ushio feared for their lives. They also had to deal with Asahi, who wanted to go to Saki, who was fighting Leugocyte as Grigio Regina, by herself. The brothers eventually manage to get through to them and were driven to Aizen Tech by Ushio to fight against Leugocyte. They transformed and defended Saki from Leugocyte, which reminded her of her brothers 1300 years ago. The next time Leugocyte launched its finisher, Grigio Regina took the hit for them and the brothers saw Saki get killed.
They then charge at Leugocyte, who beats them. Just as they were about to be finished off, Mio locks their Gyros. They then saw a large portal open up above the Aizen Tech building. Rushing there, they learned of Mio's plans and confronted her, trying to convince her to stop and they were later backed up by Ushio. Jumping out the window, the brothers transform once more. The brothers fight against Leugocyte, and seeing her sons do so, Mio stopped her plans. They were nearly defeated until they were rescued by Asahi, who became the Makoto Crystal, which they used to finish off Leugocyte via the Shin Vortex Buster.
Afterward, the Minato family reflects on who and what Asahi really is and accept that she has gone. However, she comes back to them, floating down from the sky. Life goes on as usual.
Ultraman R/B The Movie: Select! The Crystal of Bond
1 year later, Katsumi still remains doubtful about his dreams while his other siblings have found theirs. Katsumi also finds out that Isami received an offer to continue his space archaeology research overseas. He has a chat with Isami, who reveals that he delayed his response to the university because he has a responsibility as Ultraman to protect Ayaka city, but Katsumi replies saying that he should go after his dream and he can take care of the city himself. However, this leaves Katsumi more confused about his own dream and future. While daydreaming about his future, Katsumi doodles on a piece of paper until his father Ushio interrupts him, being interested in what his son drew. An old baseball with the word "dream" written on it fell off the shelf, which reminded him of his old friend Yukio Toi, who wanted to become a game creator when they were young. Katsumi pays him a visit but was shocked with what happened to Yukio, who had given up on his dream and resorted to gaming to keep himself going. After a tense conversation in which Yukio calls out Katsumi for abandoning his own dream of
going to university, Katsumi leaves but is called by his father and brother who suspect that Asahi is dating someone. It turns out to be Riku Asakura, but their conversation is cut short when Bemstar and Gan-Q appear. Ultramen Rosso, Blu and Geed fight them together and rescue Pega, who was stuck inside Bemstar and Gan-Q's linked inner dimensions. The Minatos invite Pega and Riku to dinner, and the latter explains how he arrived in their universe. Asahi and Riku talk about their pasts, with Katsumi and Isami overhearing them, but Katsumi gets even more confused about his dreams after hearing how firmly Asahi believes in her dream.
Katsumi visits Yukio again to try to convince him not to give up, but the result is the same as before, and Katsumi leaves the baseball in front of his door before leaving. His frustrations reach Ultraman Tregear who tempts him to go to Planet Hostar 21 as Ultraman Rosso to save a group of Pigmon from Mecha Gomora. Tempted by his words, Katsumi destroys Mecha Gomora. Much to his shock, Katsumi sees Yukio there, who transforms into Snake Darkness and beats him easily, leaving him stranded on the planet. Tregear later shows him Blu and Geed fighting Snake Darkness together and tells him how disposable and replaceable he is. Two hours later, Katsumi falls weak from dehydration but is saved by a grateful Pigmon who gives him some water. He is later contacted by his family and Riku by utilizing Pega's Dark Zone. He helps them identify which planet he is on, which allows them to use the Hadron Collider at Aizen Tech to bring him back home.
Katsumi, Isami, Riku and Asahi battle Snake Darkness as Ultraman Ruebe, Geed and Grigio Regina respectively and initially had the upper hand until Tregear interrupted the battle and overpowers them. Even when Grigio Regina evolves into Ultrawoman Grigio and re-energizes the three other Ultras, their power is still not enough. Geed is defeated but encourages the Minato siblings to never give up on their bonds, and they summon the Makoto Crystal, which allows them to fuse into Ultraman Gruebe. Geed also returns as Ultimate Final, and they fight Tregear and Snake Darkness. They eventually overpower the both of them, and Gruebe uses his three finishers on Snake Darkness, with the Gruebing Beam purifying him and turning him back into Yukio, who is picked back up by Katsumi and goes back home with his mother.
Later, Katsumi finds out that the doodle he drew was used by his father as a shirt design, which got very popular. He also announces to Ushio that he wants to take up fashion design, and Ushio recommends him to go to Milan in Italy to study under a friend of his. Katsumi accepts the offer and a while later, he and Isami go down their separate paths, pursuing their own futures.
Ultraman Taiga The Movie: New Generation Climax
After sealing Grimdo, the New Generation Heroes lost their ability to transform, and went to Taiga's Earth to protect Hiroyuki Kudo. Katsumi, Isami and Riku set up a shop called Ginga Quattro Market (銀河クワトロマーケット Ginga Kuwatoro Māketto) as a front in order to blend in, and made a contract with EGIS so that they could stay close to Hiroyuki and protect him. When a gang of aliens appeared, intending to steal the Ultramen's Bracelets from Hiroyuki and escape before Grimdo arrived, Katsumi and Isami defended him from a Hupnath, Lecuum, Alien Pedan, Alien Serpent, Alien Keel and Alien Shaplay using handmade replicas of their R/B Sluggers. Grimdo landed on Earth, and Hiroyuki gave the Rosso-let and Blu-let back to Katsumi and Isami respectively, restoring their R/B Gyros, and the three of them transformed and fought Grimdo. However, they were no match for the beast and were about to be defeated until Ultraman Taro arrived to rescue his son. Soon, Taro fell for Tregear's trap and was possessed by Grimdo after executing the Ultra Dynamite on it. Now under the monster's control, Taro assaulted the three Ultras and forced them to revert.
Katsumi was troubled by Taro's possession, though Isami had reassured him that everything would work out when they work together, and also told him that he found out that the flow of time in this universe was different form their home world's. After confronting Kirisaki, the New Generation Heroes transformed to fight against Tregear, Taro, and a monster army revived from their Rings. The brothers were having trouble due to Grimdo's power-ups, but their sister Ultrawoman Grigio suddenly arrived and allowed them to fuse into Ultraman Gruebe, defeating the strengthened Gorothunder. Afterwards, Tregear offered himself to Grimdo, who had been released from Taro's body. This caused Grimdo to swallow him and grow to giant size, and regain its full power. The New Generation Heroes consecutively use their finishers against Grimdo, but to no effect. Just was they were about to be blasted by Grimdo, Taro protected the New Generation Heroes with a barrier and told them to pour their energy into Taiga's Ultra Horns. Upon doing so, Hiroyuki received the New Generation Eye and transformed into Ultraman Reiga, and defeated Grimdo.
With the battle over, the New Generation Heroes gave some parting words to Hiroyuki before leaving for their home worlds.
Katsumi takes a R/B Crystal from the R/B Crystal Holder and flips out the side horns of the crystal. He then inserts the crystal and the R/B Gyro opens. The Gyro is placed at chest level and the handles are pulled twice. Katsumi then thrusts the Gyro forward and pulls the handles one last time and places the Gyro on his chest, before transforming utilizing the elemental power of the crystal. When swapping crystals with Isami, instead of getting the crystal from the holder, the new crystal will appear and fall from above. The same sequence continues afterwards.
"Enshrined by Fire! Crimson Flame!"
- ―Activation announcement for Flame
"Enshrined by Water! Azure Ocean!"
- ―Activation announcement for Aqua
"Enshrined by Wind! Violet Cyclone!"
- ―Activation announcement for Wind
"Enshrined by Earth! Amber Terra!"
- ―Activation announcement for Ground
"The power of siblings become one!"
- ―Transformation announcement w/ Kiwami Crystal
"Enshrined by Extremity! Golden Universe!"
- ―Ruebe's transformation catchphrase
The sequence begins as both brothers take the Ultraman and Belial Crystals respectively, flip out the horns of the crystal and then insert the crystal as their R/B Gyro opens. The Gyros are thrust forward and the handles are pulled thrice. This causes both crystals to merge along with the Taro, Ginga, Tiga and Victory Crystals as well to form the Kiwami Crystal.
Katsumi opens the Kiwami Crystal by pressing on the side button to reveal its Kanji letter while Isami stands by his side, before placing it onto his Gyro. He then thrusts the Gyro forward and pulls the handles one last time and places the Gyro on his chest, before the two siblings transform into Ruebe. They no longer need to use the Ultraman and Belial Crystals after their first merger.
"Overlap! The Three Souls!"
- ―Transformation announcement w/ Makoto Crystal.
"Enshrined by Reality! Immortal Truth!"
- ―Gruebe's transformation catchphrase
The Minato Siblings join their hands, which summons the Makoto Crystal. Katsumi then presses the side button, opening up the crystal while Isami and Asahi stand by his side, before placing it onto his Gyro. He then thrusts the Gyro forward and pulls the handles one last time and places the Gyro on his chest, before the siblings transform into Gruebe.
Powers and Weapons
- R/B Gyro: Katsumi possess this device in order to transform into Ultraman Rosso.
- Visual Linking: If both siblings touch their R/B Gyros, they can perceive each other's sense of vision.
- R/B Crystal Holder Rosso: A crystal holder that allows Katsumi to store his R/B Crystals.
- R/B Crystals: Katsumi uses the R/B Crystals in conjunction with the R/B Gyro in order to assume the various elemental forms of Ultraman Rosso, it seems that he shares the said crystals with Isami.
- R/B Slugger Rosso: Katsumi can wield this weapon during combat against foes as Rosso.
- Makeshift R/B Slugger Rosso: Katsumi uses a pair of handheld stick weapons in combat and training when he is not transformed as Rosso.
- Orb Ring NEO: Katsumi uses the Orb Ring NEO to activate the various attacks of Orb as Rosso.
- R/B Kourin: Katsumi wields the R/B Kourin Rosso while fighting as Ruebe.
R/B Crystals in Possession
Although both siblings became separate Ultramen, they shared the same collection of R/B Crystals and thus, only a single power can be used at a time. Outside both the transformation scene and as Ultramen, Katsumi is suspected to hold the auxiliary R/B Crystals.
- Transformation Crystals
- Ultraman Taro: Obtained simultaneously with the Gyros and R/B Crystal Holder.
- Ultraman Ginga: Obtained simultaneously with the Gyros and R/B Crystal Holder.
- Ultraman Tiga: Obtained after digging out the Crystal by combining Rosso and Blu's attacks.
- Ultraman Victory: Obtained after finding it inside a mountain cave during their training.
- Kiwami Crystal: Merged from Taro, Ginga, Tiga, Victory, Ultraman and Belial Crystals. Used to transform into Ultraman Ruebe.
- Makoto Crystal: Summoned by the Minato Siblings. Used to transform into Ultraman Gruebe.
- Auxiliary Crystals
- Ultraman Zero: Received from Kumashiro Matsuo.
- Ultraseven: Received from Kumashiro Matsuo.
- Ultraman X: Received from Kumashiro Matsuo.
- Ultraman Orb (Orb Origin): In the form of Orb Ring NEO.
- Ultraman Belial: Received from Asahi Minato.
- Ultraman: Received from Asahi Minato, used to summon the Kiwami Crystal with Belial's crystal to transform into Ruebe.
- New Generation Heroes Crystal: Obtained simultaneously with the Kiwami Crystal.
- Alongside Isami, their status as Ultra Hosts whose disappearance of a parent laid an impact to their life is similar to Shin Asuka of Ultraman Dyna. Moreover, Katsumi's passion for baseball is another similarity to Asuka.
- Katsumi was born on the 23rd of May in 1995. His blood type is A.
- The official English translation of the activation announcements are highly inconsistent: "Let's go with", "Enshrined by", "Element of", "I don".